Nowadays, traditional Roller Compacted Concrete (RCC), a zero-slump concrete used in pavements as an alternative to asphalt, is mixed in a central mix plant or using a continuous flow pug mill. RCC is required to have zero-slump since the concrete mixture needs to support a roller on its unhardened state. For effective consolidation, the concrete mixture needs to be dry enough to prevent sinking of the roller or vibratory equipment but plastic/wet enough to allow satisfactory distribution of the binder during the mixing and vibratory compaction operations. The zero-slump consistency is the adequate for this aim. RCC is normally placed using an asphalt paver (widely available, cost effective and versatile with respect to the size and width of the road to build) and/or a roller or only a roller once the RCC concrete has been distributed evenly to compact the concrete on the sub-base.
Pug mills have been around since early 1800s and are a piece of machinery used to grind and mix wet and dry materials, usually clay or asphalt, but also for RCC. It is a mobile equipment, erected on site. Generally, a pug mill consists of one or more containers and one or more rotating arms with blades or paddles attached to them. It acts as a blender, forming a smooth material that is easy to work with.
Pug mills are used from mid-size to high-volume applications. Typical pug mill capacities range from 100 m3 to over 400 m3 per hour.
Central mix plants are equipped with their own mixer. However, zero-slump concrete is very problematic to extract from the mixer and is more difficult to clean, since it causes more buildup and requires longer cleaning time. When using a central mix, transportation of RCC is done through means of a dump truck.
Both methods need special equipment (pug mills or dump trucks), not readily available for most ready-mix producers, representing a heavy investment.
Also, an extra disadvantage presented by the pug mill is that, since it is a continuous method, one has little or no control over the mix proportioning—dosage of fine and coarse aggregates as well as of sand, cement and water—, leading to homogeneity consistency problems, yielding to a product poor in consistency, with differential shrinkages, cracks formations on the placed concrete etc.
The continuous pug mill is not suitable for small applications, since the continuous pug mill is employed in high-volume applications, typically having a capacity ranging from 100 to over 400 m3/hr. These capacities are far too much compared to what is needed for small projects, making RCC a poor choice for such jobs. For smaller projects, the ideal method would be using conventional equipment employed for ready-mix, however drum mixer trucks are not appropriated due to impossibility to discharge conventional RCC from the chute, due to its zero-slump consistency. For smaller capacities/projects, there is the need for a new solution.
Pugs are usually associated with special concrete pavers (not RCC) that are huge and expensive equipments designed for large and long highways with multi lanes in order to absorb the costs of such equipment. Concrete pavers normally would not require any post-process rolling.
Traditional ready-mix equipment encompasses:                Wet mix plant, also called a central plant, where a concrete batch is made up by an operator before it is loaded into the truck. These plants have a mixer and offer producers more control over the quality and consistency of the concrete mix.        Dry mix plants are plants without a mixer, where the dry components of concrete are weighted and loaded separately into a mixer, normally the concrete truck. Water is then added and the final mix is made. Once the water is added, the mixer starts to rotate to maintain the material's liquid state until it is ready to be discharged into the truck.        Concrete trucks, also called in-transit mixers, are made to transport concrete to the jobsite while mixing it. They can be loaded in any of the mix plants mentioned above; they maintain the material's liquid state by turning the drum until delivery. The interior is fitted with a spiral blade which, in one rotational direction, pushes the concrete deeper into the drum (direction the drum rotates while transporting the concrete to the jobsite) and, turning on the other direction, discharges the concrete out of the drum. From there, the concrete can be unloaded by a chute or into a concrete pump.        
But typical ready-mix equipment yields various problems and precludes their use for RCC nowadays:                Discharging of a zero-slump concrete from a wet mixing plant, also known as central plant, is difficult, promotes buildup of material in the equipment, therefore longer cleaning procedures are needed.        Dry mix plants (where the concrete truck is operating as a mixer) cannot be used directly since zero slump concrete could not be discharged from the concrete truck, making the downhill step of the pavement placing, including evenly distribution of the material and flattening with a roller, impossible.        Delivery of a no zero-slump concrete is not accepted for RCC; a zero slump concrete is needed to comply with the final product's characteristics—the concrete mixture needs to be dry enough to prevent sinking of the roller or vibratory equipment but plastic/wet enough to allow satisfactory distribution of the binder during the placement, including homogeneously distribution of the material and/or vibration and rolling.        
Therefore, neither dry mix or wet mixing plants and related concrete transportation equipment can be used to successfully achieve RCC delivery.
However, the use of conventional ready mix production and transportation would be ideal in terms of production capacity (4 to 100 m3 per hour) for smaller or shorter roads than highways and multilane roadways. Those smaller projects would use the nominal plant capacity and could not use the huge production related to pug mill technology. Furthermore, pug mill has to work permanently (no stop and restart) since the stoppage will affect the consistency, homogeneity of the mix and consequently, the final product's quality.
The ideal method would pass by using traditional ready-mix equipment, but due to the zero-slump consistency, it is very difficult if not impossible to unload the material from the ready-mix trucks.
Furthermore, zero slump concrete would require more sophisticated equipment to homogeneously distribute the concrete on the sub-base before compaction, typically said distribution is done using a dedicated paver.
A paver is a piece of equipment used to lay asphalt or zero-slump concrete on the sub-base when a pavement, road, bridge, parking lot or other such infrastructure is being built. It lays the asphalt or concrete flat and provides minor compaction before the roller.
A roller is a vehicle that compacts asphalt or concrete, but also soil or gravel during the construction of infrastructure using those said materials.
Existing inventions describe methods wherein residual, unset concrete is transformed into granular materials that can be used as aggregates. No invention has so far disclosed a method to granulate liquid, fresh concrete and further use this concrete as RCC or any additional application other than recycled aggregates.
JP 3147832 describes a material for the treatment of residual concrete which allows the recycling of remained concrete. The aforementioned material is made of a super-absorbing polymer in powder or granular form preserved in a casing formed of water-soluble paper.
When the material is added into the mixer where the residual concrete is, the casing of water-soluble paper dissolves and the super-absorbing polymer gets in contact with the residual concrete. Through the rotation of the mixer, the super-absorbing polymer absorbs part of the water present in the residual concrete and swells, forming a gel which contains cement and other fine particles. This arrangement covers the aggregates and produces a granular material which can be discharged from the mixer and used as a roadbed filling material.
JP 2009126761 discloses a flocculating agent for agglomeration of surplus ready-mix concrete in a drum and preventing the fluidity of the ready-mix concrete. The flocculating agent for agglomeration of surplus ready-mix comprises a polymer absorber as a dispersant which is selected from the group consisting of polyacrylics, polyvinylalcohols, polysaccharides and proteins and capable of absorbing water in a dispersive medium, including organic solvents, a salt solution or the like.
WO2012084716 describes a method for producing aggregates from unset residual concrete using both flash setting accelerators, which include calcium aluminate hydrates forming compounds and sodium silicates, plus a super absorbent polymer, specifically cellulose, chitosan, collagen and other synthetic polymers. Both these ingredients are mixed directly in the truck mixer until granular materials are formed. When the flash setting accelerators mentioned in the invention are added to the concrete surplus, they react with the water to form calcium aluminate hydrates; the consumption of these water molecules causes the drying of the residual concrete and a sharp reduction of the workability. Then, the super-absorbent polymer absorbs additional water molecules and swell, forming a gel network structure which incorporates cement, the calcium aluminate hydrates crystals and the other fine components of the concrete, like sand and fillers, forming a granular material.
It can be easily understood that the combination of admixtures in this case aims at accelerating the set of the concrete to produce hardened aggregates in the shortest time possible. Therefore, the present invention proposes a unique and novel method to use conventional ready mix equipment to mix and to deliver concrete to manufacture roller compacted concrete roads, using an asphalt paver or motor grader or a roller or any combination of them.